The present invention relates to power mining shovels and in particular to the swing gear and bearing assembly coupling the upper rotating portion of the power shovel to the lower stationary portion.
Power shovels generally comprise an upper rotatable portion coupled to a lower portion which is stationary with respect to the rotatable portion but has treads for forward and reverse movement of the shovel. The upper portion includes the frame and the power units to which is attached a boom and on the outer end of the boom is a dipper or a shovel. A gear and bearing assembly couples the upper portion to the lower portion so that the upper portion can rotate to either side to pick up materials with the dipper or shovel. Thus, the bearing and gear assembly couples the upper portion with the lower portion for relative rotation and is driven by a large motor having a driving gear thereon. Since these machines are of extremely large size and can handle anywhere from 25 to 65 cubic yards per dipper or shovel, it is easy to understand that a great deal of pressure or force is applied to and wear occurs on the gear and bearing assembly which couples the upper portion to the lower portion for relative rotation.
The gear and bearing assembly comprises a gear rigidly attached to the lower stationary frame, a lower bearing rail attached to or associated with the gear, a bearing assembly rotatably placed on the lower bearing rail, and an upper bearing rail assembly attached to the upper frame assembly for resting on the bearing assembly for rotation of the upper frame assembly. The gear itself is of unitary construction and is concentrically located about a center journal which locates the pivot point about which the upper frame assembly rotates with respect to the lower frame assembly. In addition, the upper and lower bearing rails and the bearing assembly itself are usually formed in segments which are coupled together to form the necessary bearing assembly upon which the upper frame rotates with respect to the lower frame. A portion of the lower bearing rails and bearing assembly and the gear protrude beyond the upper frame assembly in the area where the upper bearing rail segments are separated thereby exposing a portion of the gear, lower bearing rails and bearing assembly for inspection. However, the bearing rail segments and the bearing segments themselves are larger than the exposed area created by the separation of the upper bearing rails and thus cannot be removed and replaced in the exposed area.
Therefore, if the gear and/or bearing rails and bearing assembly segments are required to be replaced, it is necessary to effect a total separation of the two assemblies by complete removal of the upper assembly from the lower assembly to allow the gear to be removed from around the center journal and replaced. Further, at least a partial separation of the upper frame assembly from the lower frame assembly is required to allow the upper and lower bearing rails and bearing assembly itself to be replaced. Because of the size of these machines, it is necessary that they be either moved to a location where heavy equipment exists which can lift the upper rotatable assembly from the lower assembly or such heavy machinery must be taken to the site where the mining shovel is located so that the upper rotatable portion of the shovel can be totally removed or at least partially separated from any contact with the lower portion as stated so that the necessary repairs can take place. Obviously this is extremely time consuming and expensive, not only because of the necessary movement of either the shovel or the heavy equipment, but because the removal of the upper rotatable portion of the shovel from the lower stationary portion is extremely difficult and a complex task which requires long periods of time.
Further, when the gear is replaced, it is obvious that it must be properly positioned about the center journal to allow proper concentric rotation of the upper portion of the shovel with respect to the lower portion when the unit is reassembled. However, each gear is specially and individually made for each lower frame assembly and, therefore, when the new gear is used to replace the old gear, a great deal of care must be taken to first position the gear correctly and concentrically about the center journal, and secondly to drill new holes and enlarge and thread old holes to provide for accurate attachment of the gear to the lower frame assembly by means of bolts in such a manner that the gear will not slip when the tremendous forces are applied to it. Thus, a great deal of time and labor is consumed in attempting to properly align the new gear and attach it to the lower frame assembly.
Thus, it is an object of the present invention to overcome the disadvantages of the prior art by providing a gear and bearing assembly which is much easier to remove and replace than in the prior art.
It is also an object of the present invention to provide a swing gear which can be removed and replaced simply by partially separating the upper rotatable frame assembly from the lower stationary frame assembly.
It is still another object of the present invention to provide a swing gear locating member on the lower frame assembly which enables accurate positioning of the swing gear and also prevents linear sliding movement of the gear with respect to the lower frame.
It is yet another object of the present invention to provide a swing gear which is formed in segments that can be removed from the lower frame assembly section by section, thereby avoiding the necessity for a complete removal of the upper frame assembly from the lower frame assembly to allow such gear removal to occur.
It is also an object of the present invention to provide a lower bearing rail and an upper bearing rail, both of which are formed in segments and a plurality of bearing segments which are detachably coupled to each other to form a circular bearing arrangement positioned between the upper and lower bearing rails whereby the bearing segments and the bearing rail segments may be removed and replaced in the exposed area formed by the upper frame assembly and the separated upper bearing rails without any separation of the upper rotatable assembly from the lower stationary assembly.